Method of forming a borehole lining or casing



INVENTOR. THOMAS O. ALLEN, 11m/L am@ ATTORNEY.

T. O. ALLEN METHOD OF FORMING A BOREI-IOLE LINING OR CASING Filed Nov.25, 1959 3,055,424 Patented Sept. 25, 1962 ire 3,055,424 METHD F FURMINGA BREHULE LINING 0R CASNG Thomas 0. Allen, Tulsa, Ghia., assigner, bymesme assignments, to Jersey Production Research Company, Tulsa, Dida.,a corporation of Delaware Filed Nov. 25, 1959, Ser. No. 855,311 2Claims. (Cl. 16a-21) This invention relates to oil and gas wells. Moreparticularly, this invention is a novel oil and gas well lining orcasing and a method for forming this lining or casing.

In the finding and production of oil and gas, the costs involved arecontinually increasing. Based on presentday costs, casing and tubingalone represent 1A of the cost of drilling and completing an oil well.Prospects for reducing this tremendous expenditure depend on finding asuitable substitute for steel tubular members, particularly casing orlining since it represents the major item. Steel is subject tocorrosion. Hence, it is necessary to incur the additional cost involvedin corrosion control.

The invention to be described herein provides the art with a low costborehole lining casing which is not subject to corrosion.

Briefly described, my invention comprises a flexible tubular member ofless diameter than the borehole. A cementitious plastic material whichhas been allowed to set in the annulus formed by the plastic tubularmember in the borehole in combination with the plastic tubular memberprovides an efficient borehole lining or casing.

lIn forming my new lining, a flexible tubular member of sufficientlength to extend to a point adjacent the bottom of the borehole is firstlowered into the borehole. The cementitious material is then pumped downthe flexible tubular member and up the flexible tubular memberboreholeannulus to fill the annulus with the cementitious material. Thecementitious material is then allowed to set. The set cementitiousmaterial and the Iflexible tubular member then comprise the lining ofthe borehole.

The flexible tubular member may be made of a plastic Imaterial suitablefor the purpose. Thus, the use of a steel casing is eliminated. Thecementitious material may consist of a low cost cementitious plasticmaterial. This eliminates the higher cost casing cement currentlyemployed.

Tests have shown that plastic squeezed to a minimum distance of 1radially from a 4%" borehole in Indiana limestone can withstand externalpressures in excess of 2,500 p.s.i. These tests further proved thatthick-walled, filled plastic linings in the same 4%" diameter holes werecapable of withstanding in excess of 4,000 p.s.i. external collapsepressures.

The invention as well as its many advantages will be further understoodby reference to the following detailed description and drawings inwhich:

PIG. l is a schematic View in elevation useful in explaining the methodof forming the lining or casing;

FIG. 2 is an enlarged sectional elevational View showing a preferredmethod of anchoring the flexible tubular member in the borehole;

FIG. 3 is an enlarged sectional elevational view showing an alternativeanchoring means;

rFIG. 4 is a view taken along lines 4-"4 of FIG. 3;

FIG. 5 is a view taken along lines 5-J5 of lFIG. 3; and

FIG. 6 illustrates a method for tying the upper end of the plastictubular member to a section of a steel casing to anchor the casing inthe wellhead with the surface pipe extending only a few feet below theearths surface.

Referring to FIG. l, a borehole 10` is shown formed from the earthssurface. The usual wellhead 12 is shown at the entrance to the borehole10. A steel casing 14 is cemented to the sides of the borehole by theconventional cement 16. The cement l1-6 and the steel casing 14 extend arelatively short distance below the surface.

A flexible tubular member 18 preferably made of plastic is shown loweredinto the borehole 10 with its lower extremity adjacent the bottom of theborehole. The length of the flexible tubular member 18 is chosen so asto extend to the bottom of the borehole and may be unwound from a reel20 which may be mounted on a truck 2.1.

To prevent the permanent formation of kinks and bends in the `flexibletubing 18, an anchoring means may be employed. A preferred anchoringmeans is shown in FIG. 2. An inflatable packer 22 is bonded to a closedbottom member 24. Teeth 26' are formed on the inflatable packer 22 andwhen the packer 22 is inflated, the teeth will bite into the boreholeside walls. A spring biased check valve 28 is formed in a side of thebottom member 24. Packer 22 is inflated by the application of pumppressure from the earths surface down the tubular member 18 throughcheck valve 28 and into the packer 22. The check valve 28 prevents thevalve from deflating.

A rupture disk 30 is formed in the member 24 at a point above the packer22. Once inflated to the proper pressure, fluid circulation can beachieved by applying additional pressure to rupture the disk 30.

Member 24 is securely connected to the bottom of flexible plastic tubing18 by means such as a clamp member 32.

FIG. 3 illustrates a second type of anchoring means which may beemployed. Referring to FIG. 3, the tubular bottom member 34 which issecurely clamped to the flexible tubular member 18 by clamp 32 has afull opening bottom. A plurality of slits 36 extend upwardly a shortdistance from the bottom of the bottom member 34. A spring biased latchdog 38 is pivotally connected -within each of the slits 36 by pivot pins40. Teeth 4Z are formed on the outer ends of each of the latch dogs 38.These teeth are shaped to bite into the side wall of the borehole uponslight upward movement of the flexible tubular member 18. Springs 44having one end connected to the member 34 and the other end Workingagainst the upper inside portion of the latch dog 38 provide the outwardbias.

The flexible tubular member 18 may be properly centered or spaced withinthe hole by the provision of a plurality of protrusions 46 which can bemolded directly into the flexible tubular member 18.

In carrying out my new method, the flexible tubular member 18 is rstlowered into the borehole `10. If the anchoring means of FIG. 2 isemployed, pump pressure is applied to inflate the packer 22 against theside walls of the borehole. If the anchoring means of lFIG. 3 isemployed, an upward pulling of the flexible tubular member 1-8 causesthe teeth `42 to bite into the side walls of the borehole and preventfurther upward movement. Further pulling or stretching on the top of thetubular member 18 employing either anchoring means straightens theflexible tubular member thereby removing bends and kinks. Thecementitious material is then pumped down the flexible tubular member 18and up the annulus formed by the flexible tubular member and the sidesof the borehole to completely flll the annulus. The pressure required tocause this flow will squeeze the plastic or other cementitious materialinto the formations to reinforce the hole wall. `Once the annulus isfull, the material can be allowed to set up. It is obvious that thematerial in the flexible tubular member must be displaced by a fluidwhich will not set. This can be done by calculating the requirements forthe annulus and displacing it through the flexible tubular member 18.Any deficiency can be made up by pumping additional material into thetop of the annulus.

After the plastic cementitious material has been allowed to set, the newcasing or borehole lining is complete. This lining or casing, as shownin FIG. 6, comprises the plastic tubular member 18 of less diameter thanthe borehole and the set cementitious plastic material 48 in the annulusformed by the plastic tubular member 18 and the sides of the borehole.

lFIG. 6 also illustrates a method for tying the upper end of the plasticor flexible tubular member 18 to a short section of steel casing, toanchor the casing in the wellhead. The wellhead 12 includes a topflanged member 50 provided with a slip fbowl for receiving slip members52. Slips 52 are provided with teeth or threads 54 for tight engagementwith the metal tubular member 56. The top of the exible tubular member18 is securely clamped by clamp S to the bottom portion of the metaltubular member 56.

The flexible tubular member 18 may be reeled into the borehole until theupper portion is about to enter the borehole. The metal tubular member56, which may be only a few feet in length, is then securely clamped tothe exible tubular member 18. The rest of the tubular member 18 and theattached metal tubular member 56 is then lowered into the borehole andsecurely anchored. The cementitious plastic material 48 is then formedin the same manner as formerly described.

The exible tubular member 18 may be formed of an epoxy resin or therelatively inexpensive phenol formaldehyde. Examples of cementitiousplastic material which may be utilized are phenol formaldehyde, epoxyresin, poly styrene resins, acrylic resins, butadiene styrene copolymerresin, -and others.

I claim:

1. A method of forming a lining in a borehole comprising the steps of:lowering into the borehole a flexible tubulal member having an anchoringmeans on the bottom thereof responsive to upward movement of the lexibletubular member and of suflcient length to extend to a point adjacent thebottom of the borehole; exerting an upward pull on the flexible tubularmember to anchor said member; and maintaining said pull while pumpingcementitious material down the flexible tubular member and up thetlexible tubular member-borehole annulus to ll said annulus with thecementitious material; and allowing the cementitious material to set,thus providing a borehole lining.

2. A method of forming a lining in a borehole comprising the steps of:taking a llexible tubular member with an anchoring means on the bottomthereof responsive to upward movement of the flexible tubular member andhaving a length such that when positioned in the borehole, its lower endwill extend to a point adjacent the bottom of the borehole and its upperend will be located at a depth substantially less than the depth of theborehole and lowering the llexible tubular member into the boreholeuntil a small portion extends above the wellhead; then holding theflexible tubular member while attaching a metal tubular member to thetop of the flexible tubular member and coaxial therewith; then loweringthe llexible tubular member and attached metal tubular member intoposition; exerting an upward pull on said tubular members to anchorthem; pumping cementitious material down said members and up the annulusformed by them to lill said annulus with the cementitious material; andallowing the cementitious material to Set, thus providing a boreholelining.

References Cited in the le of this patent UNITED STATES PATENTS 52,523Bryson Feb. 13, 1866 303,423 Duncan et al. Aug. 12, 1884 1,647,003 HuberOct. 25, 1927 2,092,042 Armentrout et al. Sept. 7, 1937 2,349,181 Lerchet al. May 16, 1944 2,690,806 Britton et al. Oct. 5, 1954 2,933,137DAudilret et al Apr. 19, 1960

